Yes, those are questions you should definitely know the answer to and can be found easily through Google or using the search function on this site. We seriously don't mind helping you or anyone else with their questions or problems, but when you ask things that can easily be found on your own, you might find some people getting frustrated and feeling like you expect everything to just be handed to you without you having to expend any effort yourself. Eventually, you might find simple questions like this will go unanswered, because the answer is all over the web. Just some friendly advice.
Subfolders: If you have NL or higher, yes you can subfolder to keep your Downloads organized.
sims2pack files. If you have them in your Downloads folders your game won't automatically extract them and put them in your game. They are self extracting files you have to double click on to start the process. If you don't have the Clean Installer (google can find it for you), I would highly suggest your download it and read all the instructions for it's use.
